CC-Link IEFB to EtherNet/IP Gateway for Printing Roller Sync
In modern high-speed gravure printing, maintaining tight registration across multiple color stations is critical. When a packaging leader in Guangdong upgraded their 8-color press with advanced absolute encoders, they faced a protocol mismatch between the existing Mitsubishi CC-Link IEFB network and the new EtherNet/IP devices. This article explores how an industrial protocol gateway solved the challenge, enabling seamless data exchange and achieving sub-0.05 mm synchronization at 250 m/min.
The Challenge: Merging Japanese and European Protocols
A large packaging manufacturer in Dongguan operates an 800 mm wide, 8-color rotogravure press. The existing control system relies on a Mitsubishi Q-series PLC with a CC-Link IEFB master module (QJ71GF11-T2) and eight MR-J4-B servo drives. To improve registration accuracy, the plant decided to retrofit Sick AFS60A absolute encoders (18-bit single-turn, 4096 multi-turn) directly on each printing roller. These encoders communicate via EtherNet/IP, creating a protocol gap with the CC-Link IEFB fieldbus.
The key requirements were:
- Maintain longitudinal registration error ≤ 0.05 mm (approximately 0.03° mechanical angle) across all eight rollers.
- Automatic compensation during splicing, acceleration, and deceleration from 30 to 250 m/min.
- Preserve the existing CC-Link IEFB architecture without major hardware changes.
System Topology and Components
The solution centers on a dedicated protocol gateway that acts as an EtherNet/IP master on one side and a CC-Link IEFB slave on the other. The complete bill of materials includes:
| Device | Model / Specification | Role |
|---|---|---|
| PLC | Mitsubishi Q03UDECPU + QJ71GF11-T2 | CC-Link IEFB master |
| Servo Drives | Mitsubishi MR-J4-B (x8) | CC-Link IEFB slaves |
| Encoders | Sick AFS60A-SIBN18 (x8), 262,144 ppr | EtherNet/IP slaves |
| Protocol Gateway | Industrial Ethernet/IP to CC-Link IEFB converter | Bidirectional data bridge |
| HMI | Mitsubishi GOT2000 | Teaching and diagnostics |
The gateway is DIN-rail mounted in the main control cabinet, powered by 24 VDC (200 mA), and rated IP20. It features two Ethernet ports for EtherNet/IP (P1/P2) and two for CC-Link IEFB (P3/P4), simplifying network wiring.
Gateway Configuration and Data Mapping
The protocol converter supports up to four EtherNet/IP slaves with a maximum of 500 bytes per station. On the CC-Link IEFB side, it can handle up to 512 bytes as a slave. With eight encoders, each requiring only 8 bytes of input (4 bytes for position, 4 bytes for velocity), the total data load is just 64 bytes—well within the gateway’s capacity.
Key configuration details:
| Parameter | Setting |
|---|---|
| EtherNet/IP Assembly Instance (Output) | 101 (encoder zeroing, preset) |
| EtherNet/IP Assembly Instance (Input) | 151 (position, velocity) |
| Requested Packet Interval (RPI) | 2 ms (500 Hz update rate) |
| CC-Link IEFB Logical Stations | 4 stations, each 16 bytes Rx / 16 bytes Tx |
| PLC Data Access | Remote registers RWw/RWr via GX Works3 |
The gateway’s built-in web server allows remote diagnostics, including encoder status, connection health, and station conflicts, significantly reducing troubleshooting time.
Step-by-Step Implementation
The integration was completed in four days, following a structured approach:
Day 1: Hardware Installation
Eight AFS60A encoders were mounted directly on the roller shafts using flexible couplings to avoid slippage. The gateway was installed on a DIN rail in the main cabinet. Shielded CAT5e cables connected the encoders in a daisy-chain to the gateway’s P1/P2 ports, while P3/P4 linked to the CC-Link IEFB star network. A 24 VDC power supply with surge protection and proper grounding ensured noise immunity.
Day 2: EtherNet/IP Master Setup
Using the gateway’s configuration software, the Sick EDS file was imported. Eight slave devices were defined with IP addresses 192.168.1.101–108. Assembly instances 101 and 151 were enabled with an RPI of 2 ms and a timeout of 12 ms. After building and downloading the configuration, the gateway’s RUN and OK LEDs indicated a healthy EtherNet/IP network.
Day 3: CC-Link IEFB Slave Configuration
In GX Works3, four generic remote device stations were added to the CC-Link IEFB network, each occupying 16 Rx and 16 Tx bytes. The gateway’s IP was set to 192.168.0.10, and remote register addresses were mapped (RWw0–RWw31, RWr0–RWr31). After downloading the parameters and restarting the bus, the ECT LED turned solid green, confirming communication.
Day 4: Data Alignment and PID Tuning
Eight position control loops were implemented in the PLC with a 4 ms cycle time, using a “position error + velocity feedforward” strategy. At low speed (30 m/min), encoder feedback was verified against printed registration marks. At full speed (250 m/min), high-speed camera inspection confirmed a maximum registration error of 0.04 mm, well within the 0.05 mm tolerance.
Performance Results and Benefits
The protocol gateway delivered immediate and measurable improvements:
| Metric | Before | After |
|---|---|---|
| Registration accuracy at 250 m/min | ~0.2 mm (optical encoder) | 0.04 mm |
| Total network latency | N/A | < 6 ms (2 ms EIP + 3.5 ms CCL) |
| Waste rate | 1.8% | 0.3% |
| Annual material savings | – | ~$58,000 (ink & substrate) |
| Downtime for troubleshooting | 2 hours | 15 minutes (remote diagnostics) |
The gateway’s industrial-grade design (-45 to 85°C operating temperature) ensured zero failures over six months of continuous operation. The built-in web server proved invaluable for remote monitoring and quick fault identification.
Key Takeaways for Control Engineers
This application demonstrates that protocol gateways are a cost-effective way to integrate disparate industrial networks without replacing existing infrastructure. When selecting a gateway for motion-critical applications, consider these factors:
- Data throughput: Ensure the gateway supports the required I/O size and update rate. In this case, 64 bytes at 2 ms RPI was easily handled.
- Ease of configuration: Look for tools that simplify EDS file import and mapping, reducing engineering time.
- Diagnostics: A web-based interface or LED indicators can drastically cut downtime.
- Environmental robustness: Industrial temperature range and noise immunity are essential for factory floors.
Conclusion
By deploying a CC-Link IEFB to EtherNet/IP gateway, the packaging plant achieved a seamless fusion of Japanese and European automation components. The 8-color gravure press now runs at 250 m/min with registration accuracy better than 0.05 mm, while waste has dropped by over 80%. This retrofit proves that with the right protocol converter, legacy fieldbus systems can be enhanced with modern devices, extending equipment life and boosting performance. As one engineer noted, “Protocol differences are no longer a barrier—choose the right gateway, and machines from different worlds can dance in perfect sync.”
